1. Field of the Invention
The present invention relates to an air pressure detecting device for a wheel for detecting the air pressure of a tire to allow the driver to recognize the air pressure of the tire even while the vehicle is being operated.
2. Description of Background Art
One air pressure detecting device for a wheel for allowing the driver to recognize the air pressure of a tire even while the vehicle is being operated is disclosed in Japanese Patent Laid-open No. Hei 10-44726 entitled xe2x80x9cTire Air Pressure Warning Device.xe2x80x9d
According to FIG. 1 of Japanese Patent Laid-open No. Hei 10-44726, the disclosed arrangement is a tire air pressure warning device that includes a valve stem 10 (the reference numeral is from the publication) mounted on a wheel rim 1. A case 2 is disposed beneath the valve stem 10 and a transmitter 7 is housed in the case 2. A pressure detector 3 is provided together with a signal processing circuit 4 and a cell 5.
While the above tire air pressure warning device is of a structure that can be mounted on a tubeless tire, it is not suitable for use on a tire with a tube.
In order to use the tire air pressure warning device on a tire with a tube, it is necessary to attach the transmitter 7 to the tire tube. However, the transmitter 7 cannot directly be attached to the tire tube.
It is therefore an object of the present invention to provide an air pressure detecting device for a wheel which can be mounted on a tire with a tube.
To achieve the above object, an air pressure detecting device according to the present invention provides for detecting the air pressure of a wheel of a vehicle which has a tire tube disposed in a tire with the air pressure detecting device being disposed between the tire tube and the rim of the wheel portion for detecting the air pressure of the tire. In the present invention the air pressure detecting device is held in contact with an outer surface of the tire tube.
The air pressure of the tire which is detected to provide effective drive information that can be known while the vehicle is being operated.
The air pressure detecting device for indicating the air pressure of the tire is disposed on the outer surface of the tire tube to allow the driver to know the air pressure of the tire even while the vehicle is being operated. Since the air pressure detecting device is of a structure that is held in contact with the outer surface of the tire tube, the air pressure detecting device can easily be mounted on an existing tire.
According to the present invention, the air pressure detecting device includes a pressure bearing plate held in contact with the outer surface of the tire tube, a pressure sensor for detecting a pressure of the pressure bearing plate, and a detecting and transmitting circuit for detecting pressure information from the pressure sensor, converting the pressure information into an electric signal, and transmitting the electric signal as a radio wave, the pressure bearing plate, the pressure sensor, and the detecting and transmitting circuit being superposed in the order named.
The pressure bearing plate, the pressure sensor, and the detecting and transmitting circuit are interposed between the tire tube and the rim of the wheel portion for indicating the air pressure of the tire, and detects the outer pressure of the tire tube for the driver to know the air pressure of the tire while the vehicle is being operated.
Since the components including the pressure bearing plate, the pressure sensor, and the detecting and transmitting circuit are interposed between the tire tube and the rim of the wheel portion and superposed in the order named, these components can be installed without the need for a special modification of the tire tube and the rim. The structure is simplified by superposing the pressure bearing plate, the pressure sensor, and the detecting and transmitting circuit in the order named.
The components do not need to be replaced but can be used continuously when the tire is replaced.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.